Morphology of Chromosomes in Ravenelia Species

Abstract

The present study reports the haploid chromosome complement of four species of Ravenelia. Earlier cytological studies have pertained mainly to species of Coleosporium (3, 5), Puccinia (6), Sphenospora (4) and Scopella (7), but the morphological details of chromosomes have not been described precisely. Teliospores were germinated on slides as described by Thirumalachar et al. (9, 10), fixed in Carnoy's fluid (30 ml acetic acid: 30 ml chloroform: 40 ml rectified spirit), and stored in 70% alcohol or passed through the alcohol grades, mordanted, washed and stained with 0.5% acetocarmine (8). The haploid complements of chromosomes were confirmed by the analysis of numerous preparations. Diakinesis quickly merges into metaphase. The chromosomes are thus arranged on the equatorial plate. The nuclear membrane and the nucleolus disappear while the spindle orients parallel to the vertical axis of the basidium. Astral rays are not discernible. Chromosome complements have been determined at metaphase I with confirmation at metaphase II of the meiotic division and in the mitotic division in the basidiospores. The chromosome complement is 8 for R. taslimii Mundk., 6 for R. breyniae Sydow, and 5 for R. hobsonii Cke. and R. emblicae Sydow (TABLE I). In each species, chromosome 1 is distinct from others both in size and shape, being relatively larger. Chromosomes 2, 3 and occasionally 4 resemble each other or chromosome 2 follows the morphological pattern of chromosome 1 rather than 3. Similarly, chromosome 3 resembles chromosome 4 except the size. Variation in morphology occurs among the chromosomes. The individual chromosomes of one species bear little resemblance with those of another species (FIG. 1). a er, K. B., and C. Thom. 1 49. A manual of th Pen cillia. The Wililkins Co., Baltimore. 875 p. a s an, S. A. 1927. Principles of soil micr biology. Bailliere, Tindall, ox, London. 897 p. 205